1. Field of the Invention
The present invention relates to a disk cartridge and disk drive unit for recording/reproducing information on/from a disk, using light or magnetism.
2. Description of the Related Art
Optical disk devices have been used widely for driving optical disks used as audio disks, videodisks, and data storage units in computers. In accordance with the improvement in memory density of the disks, demand has been increased for compact optical disk devices capable of recording and/or reproducing information with high density. As well as audio or video (AV) apparatuses, personal computers are getting smaller and more portable and hence, the optical disk devices also are desired to be smaller and thinner.
An optical disk capable of recording generally is accommodated in a disk cartridge to avoid adhesion of dust and fingerprints thereon. In a disk drive unit for recording/reproducing information by loading such a disk cartridge, a shutter is opened to expose part of the disk during the loading of the disk cartridge. In a state where the disk cartridge is located at a predetermined position, the disk is subject to chucking to be rotatably driven. An optical head for recording/reproducing information opposes the disk through an opening opened by the shutter and radiates light via an objective lens.
In the case of a magneto-optical disk, while an optical head radiates light forming a light spot to heat a magnetic recording film of the disk, a magnetic head applies a magnetic field to the magnetic recording film to record information. To reproduce the information, the optical head reads the changes in magnetizing directions on the magnetic recording film.
In a drive unit for such a magneto-optical disk, a magnetic head is supported so as to face the disk from the opposite side of the optical head. A supporting member of the magnetic head is connected to the optical head, and the supporting member and the optical head are integrally fed in the radial direction of the disk to scan an area between the inner periphery and the outer periphery of the disk.
Now, the structure of a conventional disk cartridge and its drive unit will be explained.
FIGS. 9A and 9B are perspective views showing the appearance of a conventional disk cartridge. FIG. 9A shows a state where a shutter 32 is closed, and FIG. 9B shows a state where a shutter 32 is opened to expose a disk 33.
FIG. 10 is an exploded perspective view showing the structure of a conventional disk cartridge.
In FIGS. 9A, 9B, and 10, an upper half 35 and a lower half 36 both having a substantially square shape in plan view are connected to each other to form a disk cartridge 31, which rotatably accommodates the disk 33. Openings 35a and 36a are respectively provided in the upper half 35 and the lower half 36 so that part of the disk 33 is exposed. The opening 36a of the lower half 36 is so largely opened as to extend to the center of the disk 33 in order that a spindle motor for rotatably driving the disk 33 can be inserted thereinto.
When the upper half 35 and the lower half 36 are connected to each other, a shutter lock 34 is incorporated. The shutter lock 34 includes a pivot 34a, a spring 34b, and an engagement portion 34c. The pivot 34a is inserted into holes in the upper half 35 and lower half 36. The spring 34b is in contact with internal walls of concave portions formed in the upper half 35 and lower half 36 so as to limit the rotation of the shutter lock 34. The engagement portion 34c is supported so as to be rotatable over a predetermined angle around the pivot 34a as a center of rotation. The engagement portion 34c is exposed in a side slot 31a formed on a side face, which is on the side where the shutter 32 slides, of the disk cartridge 31. The engagement portion 34c is rotated inwardly to be retracted when an external force is applied from the outside. At this time, the spring 34b is deformed elastically to generate a reaction force. The engagement portion 34c is returned to the initial position when the force is released.
FIG. 11 is a perspective view showing the shape of a shutter. The shutter 32 is formed of a sheet having a cross section of a substantially angular U-shape. The shutter 32 has a sufficient size to cover the openings 35a and 36a of the disk cartridge 31, and is provided with protrusions 32a and 32b, a hook 32c, and a tip hole 32d, which are formed by bending the sheet.
FIG. 12 is a perspective view showing a lower face (the face on the side of the lower half 36) of the conventional disk cartridge. After the upper half 35 and lower half 36 are connected to each other, the shutter 32 is inserted in the direction indicated by the arrow X and the protrusions 32a and 32b are inserted into a guide slot 36b provided in the lower face of the lower half 36, thereby slidably holding the shutter 32 in the direction indicated by the arrow Y. When the shutter 32 slides to a position where the openings 35a and 36a are covered, a hook 32c is engaged with a notch in the engagement portion 34c of the shutter lock 34. A locked condition of the shutter 32 is established so that the shutter 32 is not opened.
The disk cartridge 31 is inserted into the drive unit in the direction indicated by the arrow Y. During insertion, a projection formed in a cartridge holder in the drive unit passes inside the side slot 31a. The projection pushes the engagement portion 34c, which is exposed in the side slot 31a, of the shutter lock 34, thereby releasing the engagement between the engagement portion 34c and the hook 32c of the shutter 32, and limits the movement of the shutter 32 in the insertion direction at the same time. As a result, when the disk cartridge 31 is more deeply inserted, the shutter 32 stays, thereby exposing the openings 35a and 36a 
On the lower face of the disk cartridge 31, a location hole 36c is formed for maintaining the disk cartridge 31 at a predetermined position in the drive unit.
Next, the structure of a disk drive unit employing the above-mentioned disk cartridge 31 will be explained.
FIG. 13 is a plan view showing the structure of a conventional disk drive unit. Further, FIG. 14 is a side cross-sectional view showing a state where the conventional disk cartridge 31 is being inserted into the conventional disk drive unit.
In FIG. 13, an upper face of a chassis 41 and a cartridge holder 51 are removed so that the internal structure of the disk drive unit can be more easily understood. Further, in FIG. 14, the cartridge holder 51 is shown by the two-dot chain line, and an illustration of the specific structure thereof is omitted.
In FIG. 13, a spindle motor 42 is mounted in the vicinity of the center of the chassis 41. Further, the chassis 41 has two guide shafts 44 and a driving shaft 46, each extending in the direction indicated by the arrow X. A feed motor 45 is connected to one end of the driving shaft 46. An optical head 43 is held by the two guide shafts 44 and spirally interconnected with a screw formed on the outer face of the driving shaft 46. Therefore, the optical head 43 is moved in the direction indicated by the arrow X by rotation of the driving shaft 46.
As shown in FIG. 14, a connecting angle member 47 protrudes from the bottom face of the optical head 43 toward the outside of the side face of the chassis 41 so as to extend above the cartridge holder 51. On the upper end of the connecting angle member 47, a magnetic head arm 48 is mounted so as to be rotatable around a pivot shaft 49 as a center of rotation. The magnetic head arm 48 is a member like a plate spring, and has a magnetic head 50 mounted to its free end. The magnetic head 50 is moved up and down by a magnetic head lifting mechanism (not shown) mounted in the upper part of the cartridge holder 51. During recording, the magnetic head 50 descends to approach a disk surface, and then slides or is floated by air.
A position of the magnetic head 50 is adjusted so as to apply a predetermined magnetic field to the position corresponding to a light spot radiated by the optical head 43. The magnetic head 50 and the optical head 43 are integrally moved by the feed motor 45 in the radial direction between the inner periphery and the outer periphery of the disk.
Further, the cartridge holder 51 is mounted in an upper part of the chassis 41 so as to be rotatable around a pivot shaft 52 as a center of rotation. When one disk is exchanged for another, the cartridge holder 51 together with the magnetic head arm 48 is upwardly sprung up so that the disk cartridge 31 is inserted thereinto. At an entrance of an inserting portion of the cartridge holder 51, there is provided an introduction portion (not shown) that is increased in inner size toward the entrance side. The disk cartridge 31 easily can be inserted with a forefront of the disk cartridge 31 in the insertion direction being in contact with this introduction portion. During insertion, a shutter lock of the disk cartridge 31 is released by the projection (not shown) formed on the inner face of the disk cartridge holder 51 and the shutter 32 is opened.
In the lower part of the chassis 41, there is provided a circuit board 54 having a control circuit for a disk drive unit and a connector for external connection mounted thereon.
FIG. 15 is a side cross-sectional view showing a state where the conventional disk cartridge has been loaded in the conventional disk drive unit.
As shown in FIG. 15, when the cartridge holder 51 having the disk cartridge 31 inserted therein is returned to the initial position, a locating pin 53 is inserted into the location hole 36c (see FIG. 12) so as to fix a position of the disk cartridge 31. At the same time, the leading end of the spindle motor 42 is inserted into a center hole of the disk 33, and a magnet incorporated in the leading end of the spindle motor 42 attracts a clamp plate 33a of the disk 33. The disk 33 is thus loaded in the spindle motor 42.
In this state, the disk 33 is rotatably driven, thereby enabling recording/reproducing of information.
In the above-mentioned structure, the connecting angle member 47 moves along the side face of the chassis 41 while the optical head 43 moves between the inner periphery and the outer periphery of the disk 33. Accordingly, a projected shape of the drive unit as a whole in the normal direction of the disk 33 is a rectangular shape having substantially the same size as that of the smallest rectangle containing the disk cartridge 31. A small recording and reproducing apparatus of a so-called jacket size thus is obtained.
Unfortunately, however, the disk cartridge and the disk drive unit with the above-mentioned structures have the following problems.
As shown in FIG. 15, if the optical head 43 and the feed motor 45 are arranged in a lower part of the disk cartridge 31 to achieve the jacket size, a thickness H1 of a shunting space for a magnetic head 50, a thickness H2 of the disk cartridge 31, and a thickness H3 of a chassis portion determine a thickness H of the drive unit. As the feed motor 45 is arranged in the lower part of the disk cartridge 31, a height (diameter) thereof limits H3 and hence, making the optical head 43 or the spindle motor 42 thinner does not serve to decrease the thickness H of the drive unit. If the feed motor 45 is decreased in height (diameter), the generated torque is reduced, thereby reducing the access speed of the optical head 43. As a result, the disk drive unit is degraded in its performance as a recording and reproducing apparatus.
In order to make the unit thinner, if a flat motor is employed as the feed motor 45 and set in such a manner that a pivot shaft of the motor is perpendicular to a disk surface, it is required to use a gear between the feed motor 45 and the driving shaft 46. Accordingly, as compared with the case where a shaft of the feed motor 45 is directly connected to the driving shaft 46, a feeding accuracy of the optical head is degraded due to a backlash of the gear and a mechanical loss.
If the chassis portion is made thinner by arranging the feed motor 45 so as to be overlapped with the disk cartridge 31 in the horizontal direction (that is to say, arranging the feed motor 45 so as substantially to coincide in height with the disk cartridge 31), a projected area (This refers to a projected area when projected in the normal direction of the disk. The same meaning applies throughout.) of the drive unit is largely expanded as compared with that of the disk cartridge 31, whereby the so-called jacket size cannot be attained.
In the case where the circuit board 54 is mounted in a lower part of the chassis 41 as shown in FIGS. 13 to 15, if the feed motor 45 downwardly protrudes, a notch has to be made on the circuit board 54 to prevent the interference with the feed motor 45. This results in a decreased area of the circuit.
These problems are particularly serious in minimizing a projected area as well as a thickness of a small-type drive unit, particularly for a disk with a small diameter loaded in portable equipment.
Further, as a unit is made thinner, it becomes more difficult to provide an introduction portion that is enlarged in size as compared with the disk cartridge 31 at an entrance of an inserting portion of the cartridge holder 51. Accordingly, insertion of the disk cartridge is made difficult, resulting in considerably degraded operability of the drive unit.
Therefore, with the foregoing in mind, it is a first object of the present invention to provide a smaller and thinner disk drive unit, and a disk cartridge for realizing such a disk drive unit. Further, it is a second object of the present invention to provide a disk drive unit whose operability is not degraded even if made small and thin, and a disk cartridge for realizing such a disk drive unit.
In order to attain the above-mentioned objects, the present invention has the following structure.
The first disk cartridge according to the present invention includes a case for rotatably accommodating a disk for recording and/or reproducing information, an opening, which is provided in the case, for exposing part of the disk, and a shutter for closing the opening. The first disk cartridge is characterized in that a planar shape of the case includes a portion that is substantially rectangular except for a forefront edge in a direction of insertion into the drive unit and a protruding round portion formed on the forefront edge in the direction of insertion into a drive unit, at least part of an outer periphery of the round portion being formed in a circular arc shape whose center substantially coincides with the center of rotation of the disk to be accommodated, and the shutter slides along with one edge that is parallel to the direction of insertion into a drive unit.
In the above-mentioned first disk cartridge according to the present invention, the protruding round portion having a circular arc portion, which is formed along the outer periphery of the disk, is formed on the forefront edge of the substantially rectangular portion in the direction of insertion into a drive unit. In other words, both corner portions on the forefront edge in the insertion direction of a conventional substantially square disk cartridge are removed. Therefore, the area corresponding to the corner portions becomes vacant when the disk cartridge is loaded in the disk drive unit, and components of the drive unit thus efficiently can be arranged therein. As a result, a thickness of the drive unit of a so-called jacket size can be decreased.
Further, this disk cartridge greatly differs from a conventional substantially square disk cartridge in appearance. Therefore, disks to be accommodated in these disk cartridges easily can be distinguished from each other.
In the above-mentioned first disk cartridge, it is preferable that the leading end of the round portion in the insertion direction into a drive unit is made thinner than the substantially rectangular portion of the case. In this preferable structure, the round portion whose leading end is thus made thinner yields an open space in upper and lower parts thereof and enables an arrangement of components of the drive unit in the open space. Accordingly, a thickness of the drive unit can be further decreased.
The second disk cartridge according to the present invention includes a case for rotatably accommodating a disk for recording and/or reproducing information, an opening, which is provided in the case, for exposing part of the disk, and a shutter for closing the opening. The second disk cartridge is characterized in that a planar shape of the case includes a substantially rectangular portion and a protruding round portion formed on a forefront edge in a direction of insertion into a drive unit, a leading end of the round portion in the direction of insertion into a drive unit is thinner than the substantially rectangular portion, and the shutter slides along with one edge that is parallel to the direction of insertion into a drive unit.
In the above-mentioned second disk cartridge according to the present invention, the protruding round portion is formed at the forefront edge of the substantially rectangular portion in the direction of insertion into the drive unit. In other words, both corner portions on the forefront edge in the insertion direction of a conventional substantially square disk cartridge are removed. Therefore, the area corresponding to the corner portions becomes vacant when the disk cartridge is loaded in the disk drive unit, and components of the drive unit thus can be efficiently arranged therein. Further, the round portion whose leading end is made thinner yields an open space in upper and lower parts thereof and enables an arrangement of components of the drive unit in the open space. As a result, a thickness of the drive unit of a so-called jacket size can be decreased.
Further, this disk cartridge greatly differs from a conventional substantially square disk cartridge in appearance. Therefore, disks to be accommodated in these disk cartridges easily can be distinguished from each other.
In each of the above-mentioned first and second disk cartridges, it is preferable that the round portion is formed so as to be gradually decreased in thickness toward the leading end. According to this preferable structure, the function of an introduction portion, which is conventionally mounted in the cartridge holder of the drive unit, is given to the round portion of the disk cartridge. Therefore, reduced-sizing or removal of an introduction portion at the entrance of the inserting portion of the cartridge holder is made possible without degrading the operability of the disk cartridge during insertion. As a result, a thickness of the drive unit can be decreased further.
Further, in each of the above-mentioned first and second disk cartridges, it is preferable that the outer periphery of the round portion has an inflection point on a side of a shutter sliding edge with respect to the leading end of the round portion and no inflection point on a side of an edge opposite to the shutter sliding edge with respect to the leading end of the round portion. That is, on the side of the shutter sliding edge, an opening, a sliding distance of the shutter, and a space for mounting a mechanism for maintaining the closing state of the shutter can be secured by gently curving the outer periphery of the round portion via the inflection point along the forefront edge of the substantially rectangular portion in the insertion direction. On the other hand, on the side of the edge opposite to the shutter sliding edge, the removed portion (notch portion) at the corner portion on the side of the opposite edge can be made large by curving the outer periphery of the round portion without an inflection point (preferably gently along the opposite edge). This serves to enlarge an open space. By arranging more components of the drive unit in the above-mentioned open space, it becomes possible further to decrease a thickness of the drive unit.
It is preferable that the above-mentioned first and second disk cartridges further are provided with a closing-state maintaining mechanism for maintaining a state where the opening is closed by the shutter. This mechanism prevents the opening from being accidentally opened, and thus avoids scratches on the accommodated disk as well as dirt and fingerprints adhesion onto the disk.
The above-mentioned first and second disk cartridge can be used with a magneto-optical disk or an optical disk accommodated therein.
A disk drive unit according to the present invention includes a head for recording and/or reproducing information with respect to a disk accommodated in a disk cartridge, a spindle motor for rotatably driving the disk, a feed motor for feed-driving the head in a radial direction of the disk, and a loading member for loading the disk cartridge, the disk drive unit having a projected shape that is a rectangle substantially coincident with a smallest rectangle containing the disk cartridge. The disk drive unit is characterized in that part of its components is arranged in at least one corner portion of the smallest rectangle containing the disk cartridge loaded in the loading member so as substantially to coincide in height with the loaded disk cartridge. What is meant by xe2x80x9cthe smallest rectangle containing the disk cartridgexe2x80x9d is the rectangle of the smallest size among those capable of containing the planar shape of the disk cartridge. Further, xe2x80x9cprojected shapexe2x80x9d means a shape projected in the normal direction of the disk surface.
In this structure, part of the components conventionally arranged over or under the disk cartridge loaded in the loading member to avoid the interference with the disk cartridge effectively can be arranged in corner portions of the smallest rectangle containing the loaded disk cartridge so as substantially to coincide in height with the loaded disk cartridge. Accordingly, a thickness of a chassis portion of the drive unit can be made thinner without increasing a projected area of the drive unit. As a result, a thin drive unit of a so-called jacket size can be obtained. Further, if the drive unit maintains the same thickness, it is possible to improve an access speed of the disk drive unit by the use of a feed motor having a larger diameter, for example.
Further, when a conventional disk cartridge of a substantially square shape is erroneously inserted into the drive unit, part of the components of the drive unit bumps against the forefront of the disk cartridge in the insertion direction, thereby preventing the disk cartridge from being loaded. Accordingly, damage to the drive unit or a disk and erroneous operation due to the insertion of disk cartridges of other standards having no compatibility with the drive unit is prevented beforehand.
In the above-mentioned disk drive unit according to the present invention, an optical head may be employed as the above-mentioned head, whereby a drive unit for a magneto-optical disk or an optical disk can be provided.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.